1. Field of the Invention
The present invention relates to an apparatus and method for processing information and, more particularly, to a technique or method for protecting the copyright of digital data of images, sounds, text, etc.
2. Description of the Related Art
Recently, with the development of information communication systems and large-capacity recording mediums, it is possible to exchange large amounts of image and sound digital data via a network, or by using a recording medium such as a compact disc read-only memory (CD-ROM), a magneto-optical disc, or a magnetic tape.
In general, digital data is easy to copy, transmit, store and is also free of quality deterioration during copying, transmission and storage. These characteristics make it easy for a third party to read or copy digital data, thereby enabling infringement of the copyright on the data. A means for preventing copying of digital data to protect the copyright on the digital data is, therefore, needed.
A method has been practiced in which a copy inhibition flag is inserted at certain positions in digital video and audio data to prevent unauthorized copying.
However, this conventional method, in which data itself is maintained in the original form, is not effective in preventing unauthorized copying of data, because data protected by this method can still be copied by dump copying, for example.
Encryption techniques have recently been proposed as alternative methods for protecting digital data. However, if digital data is encrypted, the data cannot be used by ordinary users who want to copy, transmit and store the data in an authorized manner.